There has been known a noise reduction device for reducing noise generated in a power conversion device that includes: a converter connected to an AC power supply; an inverter connected to a DC output side of the converter; and a DC smoothing capacitor connected to a DC intermediate circuit (see Japanese Patent Application Publication No. 2002-252985). The noise reduction device is a device configured to reduce a noise current which flows on the power conversion device in response to the turning on and off of semiconductor switching elements that constitute the inverter. The noise reduction device includes: a noise current detection unit configured to detect the noise current; and a noise compensation current supply unit configured to generate a noise compensation current for reducing the detected noise current, and to supply the noise compensation current to the power conversion device. The noise compensation current supply unit is an element whose output current is controlled according to a detection signal from the noise current detection unit. The noise compensation current supply unit includes a series circuit including transistors each having a breakdown voltage smaller than a voltage of the DC intermediate circuit; and Zener diodes.
However, there is a problem that the transistors and the Zener diodes cannot perform high-speed operations against high-frequency switching noise, thereby failing to suppress the noise.